1. Field of the Invention
The present invention relates to an improvement in a multicylinder engine intake system comprising: a plurality of intake paths communicating with intake ports of a multicylinder engine; a plurality of throttle valves for opening and closing the intake paths; a plurality of bypasses having upstream ends opened to atmosphere or the intake paths on upstream sides of the throttle valves, and having downstream ends opened to the intake paths on downstream sides of the throttle valves; and a common bypass control valve which opens and closes the bypasses.
2. Description of the Related Art
A bypass control valve in a multicylinder engine intake system is operated to regulate the amount of first idling air supplied to the engine through bypasses in order to appropriately control a first idling rotational speed mainly during engine warm-up operation.
A multicylinder engine intake system of this type is known from, e.g., Japanese Patent Application Laid-open No. 2003-129924.
In the multicylinder engine intake system disclosed in Japanese Patent Application Laid-open No. 2003-129924, the bypass control valve is horizontally placed, leading to a possibility that fuel or water droplets entering the bypasses stays around the bypass control valve, and thus there is a need to provide an expensive sealing means for the bypass control valve. There is also a possibility that the fuel or water droplets staying around the bypass control valve hinders appropriate control of the amount of first idling air by the bypass control valve.